1. Field of the Invention
The present invention relates to a method for controlling a cogeneration system, and, more particularly, to a method for controlling a cogeneration system, wherein whether or not a generator included in the cogeneration system is to be driven is determined in accordance with the operation load of an air conditioner included in the cogeneration system.
2. Description of the Related Art
FIG. 1 is a schematic view illustrating a conventional cogeneration system.
As shown in FIG. 1, the conventional cogeneration system includes a generator 2 to generate electric power, a drive source 10, which operates to drive the generator 2, and generates waste heat during the operation thereof, such as an engine (hereinafter, the drive source 10 will be referred to as an “engine”), a waste heat recoverer 20 to recover waste heat generated from the engine 10, and a heat consumer 30 to utilize the waste heat recovered by the waste heat recoverer 20, such as a thermal storage tank.
The electric power generated from the generator 2 is supplied to various electric home appliances including the air conditioner 4 and various home illumination devices. To this end, the generator 2 is connected with the electric home appliances via power lines 3.
The air conditioner 4 includes compressors 5, a 4-way valve 6, indoor heat exchangers 7, expansion devices 8, and outdoor heat exchangers 9.
When the air conditioner operates in a cooling mode, each compressor 5 compresses a refrigerant introduced thereinto. The compressed refrigerant passes through the 4-way valve 6, outdoor heat exchangers 9, expansion devices 8, indoor heat exchangers 7, and 4-way valve 6, in this order, and returns to the compressors 5. In this case, each outdoor heat exchanger 9 functions as a condenser, and each indoor heat exchanger 7 functions as an evaporator to absorb heat from indoor air.
On the other hand, when the air conditioner operates in a heating mode, the refrigerant compressed in each compressor 5 passes through the 4-way valve 6, indoor heat exchangers 7, expansion devices 8, outdoor heat exchangers 9, and 4-way valve 6, in this order, and returns to the compressors 9. In this case, each outdoor heat exchanger 9 functions as an evaporator, and each indoor heat exchanger 7 functions as a condenser to heat indoor air.
The waste heat recoverer 20 includes an exhaust gas heat exchanger 22 to absorb heat from exhaust gas discharged from the engine 10, and a cooling water heat exchanger 24 to absorb heat from cooling water used to cool the engine 10.
The exhaust gas heat exchanger 22 is connected with the heat consumer 30 via a first heat supply line 23. Accordingly, the exhaust gas heat exchanger 22 can transfer the waste heat absorbed from the exhaust gas of the engine 10 to the heat consumer 30 via the first heat supply line 23. As mentioned above, the heat consumer 30 may be a thermal storage tank.
The cooling water heat exchanger 24 is connected with the heat consumer 30 via a second heat supply line 24. Accordingly, the cooling water heat exchanger 24 can transfer the waste heat absorbed from the cooling water of the engine 10 to the heat consumer 30 via the second heat supply line 24.
In the conventional cogeneration system, however, the engine 10 is driven irrespective of the load of the electric home appliances including the air conditioner 4 and various illumination appliances. For this reason, there is a problem in that the conventional cogeneration system is uneconomical when the load of the electric home appliances is low.
Furthermore, the conventional cogeneration system has a problem in that the waste heat of the engine 10 is utilized only in the heat consumer 30, which may be a thermal storage tank, without being utilized in the air conditioner 4, so that the efficiency of the cogeneration system cannot be maximized.